---
title: QuickTime audio codec type
framework: quicktime-file-format
role: article
role_heading: Article
path: quicktime-file-format/quicktime_audio_codec_type
---

# QuickTime audio codec type

## Overview

Overview Feature Values This is the four-character-code found in a sound sample description. Examples: 'mp4a', 'twos'. Writer Responsibilities A writer of the QuickTime audio codec type feature should record the four-character-code corresponding to the QuickTime audio format type or types also recorded in the sound track’s sample descriptions. note: A writer that records the QuickTime Audio Codec type for the 'mp4a' codec is encouraged also to write the MPEG-4 Audio Codec feature. Feature Value Algorithm The feature value is the audio codec type read from a SoundDescription structure’s dataFormat field. If there are multiple sample descriptions with different audio codec types, either all QuickTime Audio Codec Type features must be recorded in the profile atom or none must be recorded. Reader Responsibilities A reader of this feature code should compare the recorded value by an equality comparison (using =) with the format codes supported by the reader.

## See Also

### Setting features

- [Table of features](quicktime-file-format/table_of_features.md)
- [Maximum video bit rate](quicktime-file-format/maximum_video_bit_rate.md)
- [Average video bit rate](quicktime-file-format/average_video_bit_rate.md)
- [Maximum audio bit rate](quicktime-file-format/maximum_audio_bit_rate.md)
- [Average audio bit rate](quicktime-file-format/average_audio_bit_rate.md)
- [QuickTime video codec type](quicktime-file-format/quicktime_video_codec_type.md)
- [MPEG-4 video profile](quicktime-file-format/mpeg-4_video_profile.md)
- [MPEG-4 video codec](quicktime-file-format/mpeg-4_video_codec.md)
- [MPEG-4 video object type](quicktime-file-format/mpeg-4_video_object_type.md)
- [MPEG-4 audio codec](quicktime-file-format/mpeg-4_audio_codec.md)
- [Maximum video size in a movie](quicktime-file-format/maximum_video_size_in_a_movie.md)
- [Maximum video size in a track](quicktime-file-format/maximum_video_size_in_a_track.md)
- [Maximum video frame rate in a single track](quicktime-file-format/maximum_video_frame_rate_in_a_single_track.md)
- [Average video frame rate in a single track](quicktime-file-format/average_video_frame_rate_in_a_single_track.md)
- [Video variable frame rate indication](quicktime-file-format/video_variable_frame_rate_indication.md)